MDA Technologies 2/2015

Split roller bearings

Split roller bearings keep icebreaker generators running Split roller bearing specialists Cooper has supplied bearings for the generators of an icebreaker operated by the Canadian Coast Guard. The on-board generators’ existing sleeve bearings had a short operational life and their maintenance required too much time and effort. To keep seas and inland waterways navigable during Canada’s long, severe winters, the Canadian Coast Guard operates close to 20 icebreakers of various classes for light, medium and heavy-duty tasks. These icebreakers are designed and equipped to navigate frozen sea. They have engines that are much larger and more powerful than those of other vessels of comparable size to be able to plough through the ice and carve a sufficiently wide navigable channel for other ships. On-board electricity is supplied by generators. Recently, problems occurred with the friction bearings of the on-board generators of one of the icebreakers, and this was followed by the same problem on other ships of the fleet. Each of the two generators has two bearings that hold the generator shaft – one fixed and one floating to allow the shaft to expand as it heats up. The existing sleeve bearings had an unexpectedly short lifespan and required excessively complex maintenance work, partly owing to restricted access to the bearings. The need for oil lubrication also presented generic problems and replacement parts from the manufacturer had long lead times. Direct drop-in replacement These problems called for a solution that did not require alteration of the generator itself: The new bearing would have to be a direct, drop-in replacement. Since the icebreakers have heavy work schedules, downtime must be kept to a minimum. The Cooper solution was to provide a high-quality split cylindrical roller bearing as a direct replacement for the existing sleeve bearings. The split bearing has a special cartridge that holds the shaft-end cover and is mounted on a standard pedestal. A support plinth and elevating pedestal were built to customer specifications to provide dimensionally identical support for the shaft. The new solution allowed rapid replacement without modification of the generator. The roller bearings are fully split up to the shaft, and the labyrinth seal is also of a split design. They have clear advantages over the previous sleeve bearings: Their design allows easy-access inspection and maintenance, since no other components need to be removed. This significantly cuts standstill times and maintenance effort. The bearings have a long service life and do not need oil lubrication, eliminating the need for pumps and filters and the risk of oil leaks. The bearings run cooler and consume less power. There is no longer a risk of damage to the shaft from bearing failure. 44 MDATechnologies 2/2015

CASE STUDY 01 02 03 Not only for marine Cooper bearings have been tried and tested in marine environments for many decades, and Cooper supplies both OEMs and subsuppliers. From offshore support vessels to ferries, military vessels, fishing boats and tugs, Cooper split bearings provide the reliability and flexibility crucial in extreme working conditions out at sea. Beside marine propulsion, they can also be found in other shipboard, transport and loading activities. The split bearing was designed in 1907 by inventor and engineer Thomas Cooper. To this day, the company he established in King’s Lynn in Norfolk, UK is a world leader in the development of split bearings. All Cooper products are made in Norfolk and sold throughout the world. Cooper’s German subsidiary – Cooper Geteilte Rollenlager GmbH – has its headquarters in Krefeld. Cooper’s full range of split roller bearings includes standard bearings such as cylindrical roller bearings and tapered roller bearings as well as special bearings including water-cooled bearings, flat thrust bearings, other solid bearings, high speed bearings, full row bearings and other special types, and large bearings over 600 mm bore size. In addition to maritime applications, Cooper bearings are used in industries including steel, mining, conventional power, cement and other building materials where operating conditions are beyond the average – including situations that are often dirty and feature extreme temperatures. Typical applications beside marine propulsion include conveyors, fans and blowers, cooling beds, continuous casters, stacker reclaimers, and many other applications, especially where bearings are in trapped positions and access is limited. www.cooperbearings.com 01 Bearing unit with split bearing from Cooper 02 Fully installed split bearing unit 03 Cooper bearing installed on the shaft About Company name: Cooper Roller Bearings Company Ltd. Group: SKF Group company Headquarters: Kings Lynn, Norfolk/UK Founded: 1907 Products: bearings, housings, seals MDATechnologies 2/2015 45